Steps to reproduce:
1. Create a new project using the Universal 3D template
2. Install Multiplayer Widgets package via Package Manager window (or add package by name: com.unity.multiplayer.widgets), and do not install com.unity.services.vivox
3. In the Project window, expand Packages > Multiplayer Widgets > Assets/Prefabs/Communication
4. Drag the "Text Chat" prefab into the Hierarchy window
5. Observe the Inspector window for the new object and its children
6. Repeat steps 4-5 for "Audio Input Device" and "Audio Output Device", then for "Create Session" from Assets/Prefabs/Session as a control
Actual results: Text Chat, Audio Input Device and Audio Output Device have each "Missing (Mono Script)" components
Expected results: the prefabs are gated with their assembly, or the package declares Vivox as a dependency, or the Inspector explains the missing dependency, The control prefab Create Session doesn't have any missing scripts
Reproducible with versions: 1.0.5 (6000.0.84f1, 6000.3.24f1, 6000.5.11f1, 6000.6.1f, 6000.7.0a6)
Tested on (OS): macOS 26.6.1 (Apple silicon)